Geoscience Reference
In-Depth Information
years to be useful for the purpose depicted in the movie
Jurassic
Park.
This would be unlikely because, as the amber is buried deep
within the earth during fossilization, temperatures can easily reach
several hundred degrees, which would surely destroy the blood cells.
An additional problem is that the amber itself often contains natural
cracks, increasing the chances that contaminants in the groundwater
that flows through the rocks in which the amber is buried will dam-
age the dinosaur genes in the blood.
Another problem is that the insect would have had to die before the
dinosaur's blood was digested in its stomach, because digestion
would also have damaged the dinosaur's genes. What's more, there is
no guarantee that the insect's last meal would have been the blood of
an extinct dinosaur, given that many other kinds of animals also
lived during the Mesozoic, including turtles, lizards, crocodiles,
pterosaurs, birds, and even our own early mammalian relatives. Fur-
thermore, it would be no easy task to remove the dinosaur's blood and
genes from the insect inside the amber. For the purposes of cloning
in the movie, the dinosaur's genes would have to be kept separate horn
the genes in the insect's body. But since we would have to cut through
the insect to get at the dinosaur's genes, it would be difficult to keep
the tissues of the two animals separate and uncontaminated.
But assuming that all this could be done, molecular biologists
have recently developed a technique called polymerase chain reaction
(PCR) to duplicate the genes enough times to produce enough
genetic material with which to do some experiments. Most of the
research done in labs around the world using this technique is
directed toward comparing the genetic codes of different animals in
order to establish their evolutionary relationships. To date, the oldest
insect DNA that has successfully been duplicated is genetic material
from a termite preserved in amber between 25 and 40 million years
ago. That was a remarkable accomplishment achieved by molecular
biologists working at the American Museum of Natural History in
New York. Nonetheless, that termite lived long after the Mesozoic
ended 65 million years ago.
The problems don't end here, either. An animal's genetic code is
like a topic containing information about how to build that particu-
lar animal. The chromosomes are like the chapters of the topic; genes
are sentences; and nucleic acids are letters of the alphabet. Because
